This study examined the effect of lowering (Study 1) and raising (Study 2) the stroke rate during high intensity breaststroke swimming. Breaststroke swimmers (N = 14) completed a dive-start 200-m time-trial. Nine of the group then completed a series of push-start 175-m swims with a controlled stroke rate of 92%, 95%, and 100% of the mean stroke rate during the last 175-m of their 200-m time-trial (Study 1). In Study 2, eight of the group swam 175-m trials at 100% and 107% of the mean stroke rate for the last 175-m of their 200-m time trial.

In Study 1, rating of perceived exertion scores were lower in the 92% trial compared to the 100% trial and there was a trend toward slower finishing times for the 92% and 95% trials compared to the 100% trial. In Study 2, no differences in heart rate, blood lactate, rating of perceived exertion, or finishing times were observed between trials.

Implication. The difference in perceived exertion ratings may be associated with biomechanical rather than physiological changes as the latter were similar between trials. The similarity between physiological and performance parameters in both studies and rating of perceived exertion scores in Study 2 appear to show that either: a set physiological capacity constrains breaststroke performance, or that a pacing strategy initiates adjustments in stroke length or other biomechanical behavior to maintain a set level of physiological activity, in order to allow the completion of the trial in the fastest possible time.